High-resistance decelerating device, particularly for insertion between two members in relative motion

ABSTRACT

A decelerating device having a casing defining internally a chamber ( 5 ) filled with a viscous fluid, e.g. silicone oil; and a movable member fitted in fluidtight manner to the casing, so as to be housed at least partly inside the chamber and immersed in the viscous fluid; the movable member has partition means for dividing the chamber substantially in fluidtight manner into at least two adjacent portions varying in volume as a function of the position of the movable member with respect to the casing; and calibrated constriction means for maintaining permanent hydraulic connection of the at least two adjacent portions of the chamber, so that the viscous fluid flows between the chamber portions as a consequence of relative motion between the movable member and the casing.

The present invention relates to a high-resistance decelerating devicefor insertion between two members in relative motion, e.g. by the actionof a spring or gravity, and for considerably slowing down motion of thetwo members.

BACKGROUND OF THE INVENTION

As is known, in top-loaded washing machines, the drum has two doorsfitted with spring-loaded hinges. When the closed doors are released,e.g. by pressing a button, springs push the doors open by rotating themradially; and, conversely, the open doors are pushed manually back intothe closed position in opposition to the springs, which are thusreloaded elastically.

Since the doors would be opened fairly sharply, thus endangering theuser, the opening movement must be damped by fitting the doors withdecelerating devices.

Generally speaking, many applications, not only electric householdappliances, but also automotive components (such as a glove compartmentdoor), involve damping the movement of two members in relativemotion—normally relative rotation but possibly also relative slidingmotion.

Known decelerating devices normally comprise a rotor (e.g. in the formof a turbine), which rotates immersed in a viscous fluid inside acasing; and the rotor is secured to one of the rotating members, and thecasing to the other. Though effective, this type of decelerating deviceis bulky, particularly radially, and in direct proportion to the amountof braking action required, and is therefore unsuitable for use in ahinge, particularly one of small radial dimensions as in the case of atop-loaded washing machine drum.

On the other hand, other known, more radially compact, deceleratingdevices simply comprise a rotating pin immersed in the viscous fluid,and therefore fail to generate a high braking torque.

SUMMARY OF THE INVENTION

It is an object of the present invention to eliminate the aforementioneddrawbacks by providing a decelerating device which, despite beingcompact, particularly radially, is capable of generating considerableresistance, is straightforward in design, and is reliable and cheap toproduce.

According to the present invention, there is provided a deceleratingdevice as claimed in claim 1.

More specifically, according to the invention, the decelerating devicecomprises a cup-shaped, cigarette-shaped casing; and a cylindrical pinfitted idly to and at least partly housed inside the casing. The pin isinserted through an open end of the casing, and comprises an axialportion housed idly in fluidtight manner inside a chamber defined in thecasing, and in which the axial portion is immersed in a viscous fluid.The pin has at least one radial rib formed along the whole length of thefirst axial portion and sized to cooperate in sliding manner with acylindrical inner lateral wall of the chamber, and an angular portion ofpredetermined size of said inner lateral wall of said chamber has asaddle-shaped projection defining a cylindrically symmetrical seat, onwhich a cylindrical outer lateral wall of the axial portion of the pinrests and slides in use. At least one annular groove is formed on therib or on the cylindrical outer lateral wall of the axial portion of thepin to connect respective variable-volume portions into which the riband the saddle-shaped projection divide the chamber.

As it rotates inside the casing, the pin thus varies the volume of thetwo chamber portions (increases one and reduces the other) by virtue ofthe movement of the rib, rotating integrally with the pin, inside thechamber; while the saddle-shaped projection, by interrupting the annularcontinuity of the chamber, prevents the viscous fluid from being simplyrotated by the movement of the rib. The viscous fluid (normally siliconeoil) is thus forced to flow from one chamber portion (the one beingreduced in volume) to the other through said at least one groove (or atleast one hole formed through the rib), which thus acts as a calibratedresistance-generating constriction for producing even a relativelystrong force (in this case, torque on the pin) opposing relative motionbetween the pin and casing.

BRIEF DESCRIPTION OF THE DRAWINGS

A non-limiting embodiment of the present invention will be described byway of example with reference to the accompanying drawings, in which:

FIG. 1 shows a longitudinal section of a decelerating device inaccordance with the invention;

FIG. 2 shows a larger-scale, three-quarter front view in perspective ofthe FIG. 1 device with the main components detached;

FIG. 3 shows a section along line III-III of the FIG. 1 deceleratingdevice;

FIGS. 4 and 5 show the same section as in FIG. 3, of two possiblevariations of the FIG. 1 decelerating device.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1 to 3, number 1 indicates as a whole ahigh-resistance decelerating device insertable in known manner betweentwo members 2 and 3 movable relatively with respect to each other andonly shown schematically by dash lines in FIG. 1 for the sake ofsimplicity.

In the non-limiting example shown, the two members 2 and 3 rotaterelatively, so that decelerating device 1 described below provides forbraking relative rotation. The principle of the invention, however, maybe applied to braking any relative motion, e.g. even sliding motion,between two members between which the decelerating device according tothe invention is insertable.

As shown in FIGS. 1 to 3, device 1 comprises a casing 4 defininginternally a chamber 5 filled with a known viscous fluid 6 (FIG. 3),e.g. silicone oil; and a movable member 7 fitted in fluidtight manner tocasing 4, so as to be housed at least partly inside chamber 5 andimmersed in viscous fluid 6.

The principle of the invention lies in providing device 1 with acombination of:

-   -   partition means, indicated as a whole by 9, for dividing chamber        5 substantially in fluidtight manner into at least two adjacent        portions 10 and 11 varying in volume as a function of the        position of movable member 7 with respect to casing 4; and    -   calibrated constriction means, indicated as a whole by 12, for        maintaining permanent hydraulic connection of the two adjacent        portions 10 and 11 of chamber 5, so that the viscous fluid 6        flows, with a given, relatively high resistance, between the two        chamber portions 10, 11 as a consequence of the relative motion        between movable member 7 and casing 4.

As explained more clearly later on, in the example shown, partitionmeans 9 are designed to also act as supporting and guide means formovable member 7 inside chamber 5 of casing 4.

More specifically, in the non-limiting example shown of relativelyrotating members 2 and 3, casing 4 is cup-shaped and of elongated,cylindrical axial symmetry like a cigarette; while movable member 7 isdefined by a cylindrical pin, which is fitted idly to casing 4, ishoused at least partly inside casing 4, clicks into an axially lockedposition inside casing 4, and is inserted through an open end 14 ofcasing 4.

Cylindrical pin 7 comprises an axial portion 15 housed idly influidtight manner inside chamber 5 to define a rotor immersed in viscousfluid 6 (FIG. 3) filling chamber 5; and an enlarged head 29 projectingfrom open end 14 of casing 4. Between axial portion 15 and head 29 ofpin 7 are interposed: a cylindrical stop surface 31 larger in diameterthan portion 15 and such as to mate idly with a cylindrical innerlateral wall 24 of chamber 5, at open end 14 of casing 4; and a collar33 which, when pin 7 is assembled inside casing 4, clicks inside acorresponding groove of matching shape formed in cylindrical innerlateral wall 24 of chamber 5, at open end 14 of casing 4. Betweencylindrical stop surface 31 and collar 33, a sealing ring 34 (FIG. 1) isinserted inside a seat on pin 7, and cooperates with cylindrical innerlateral wall 24.

Head 29 and the end 18 of casing 4 opposite open end 14 have known meansfor angular connection to relatively rotating members 2 and 3, e.g. aradial tab or projection 19 on head 29, and a tangential faced or flatportion 20 (FIGS. 2 and 3) at end 18, so that, in use, pin 7 and casing4 are rotated relatively by members 2 and 3 —casing 4 angularly integralwith member 2 (e.g. a top-loaded washing machine drum), and pin 7angularly integral with member 3 (e.g. a swing door of said top-loadedwashing machine drum).

Said partition means 9 comprise at least one radial rib 9 a extendingaxially along the whole length of axial portion 15 of pin 7, and sosized as to cooperate in sliding manner, in use, with cylindrical innerlateral wall 24 of chamber 5 of casing 4; and a saddle-shaped projection26 extending along an angular portion of given size of inner lateralwall 24 of chamber 5 (FIG. 3). Projection 26 defines a cylindricallysymmetrical seat, on which part of a cylindrical outer lateral wall 25of axial portion 15 of pin 7 rests and slides in use.

Pin 7 is thus rotated inside chamber 5 in precise, balanced manner(largely on opposite sides) by rib 9 a and projection 26, and onsubstantially continuous supports preventing (or at least greatlyreducing) radial flexing of the pin.

Moreover, rib 9 a and projection 26 divide chamber 5 in substantiallyfluidtight manner into adjacent chamber portions 10, 11; andsaddle-shaped projection 26 interrupts the annular continuity of chamber5, and prevents the viscous fluid 6 in the chamber from being rotated bythe relative rotation between portion 15 of pin 7 and casing 4.

Projection 26 also acts as an angular stop for the rotation of pin 7, byarresting axial rib 9 on opposite sides.

The end of axial portion 15 of pin 7 opposite head 29 of pin 7 matesidly with and rests axially on casing 4 inside a cylindrical seat 36defined by a recess formed inside chamber 5, in an end wall 38 of casing4, and facing open end 14 of casing 4. Both the opposite ends and theintermediate portion of pin 7 are therefore supported and guided, asstated, by casing 4 and by saddle-shaped projection 26 and rib 9 a,regardless of the angular position of pin 7 with respect to casing 4.

In a variation not shown for the sake of simplicity, device 1 mayobviously comprise a number of radial ribs 9 a in different angularpositions, so as better to support pin 7 as it rotates; in which case,chamber 5 is divided into more than two adjacent chamber portions, andin particular, in the case of n ribs 9, into n+1 adjacent chamberportions, at least two of which are always separated by projection 26.

Calibrated constriction means 12 comprise one or more annular grooves 12(two in the example shown, though any number may be provided)interrupted by radial rib 9 a and formed in cylindrical outer lateralwall 25 of axial portion 15 of pin 7.

End 18 of casing 4 is preferably provided with an axially projecting pin17 for supporting, in known manner not shown for the sake of simplicity,a torsion spring for producing, in given conditions, relative motionbetween members 2 and 3, e.g. the door-release spring of a top-loadedwashing machine drum.

Device 1 as described is therefore fairly compact radially, and so muchso as to be easily incorporated in a small-size hinge. At the same time,however, it is capable of producing considerable resistance, which istheoretically independent of the external size of the device, bydepending solely on the viscosity of fluid 6 and on the size of theradial passages connecting chamber portions 10 and 11, and by projection26 preventing fluid 6 from being simply rotated, with friction, byrotation of pin 7 and the elements integral with it.

In the FIG. 4 variation, in which details similar to or identical withthose already described are indicated using the same reference numbers,the calibrated constriction means according to the invention comprise atleast one groove 112 formed, circumferentially with respect to the axisof symmetry of pin 7, in a cylindrically symmetrical surface defining anend edge 113 of each rib 9 a provided. In use, edge 113 cooperates influidtight manner with cylindrical inner lateral wall 24 of chamber 5,but the viscous fluid 6 moved by rotation of pin 7, as a consequence ofrib 9 a, can still flow between chamber portions 10 and 11 alonggroove/s 112.

Similarly, in the FIG. 5 variation, grooves 12 or 112 are eliminated,and the calibrated constriction means comprise at least one hole 212formed, circumferentially with respect to the axis of symmetry of pin 7,through a root portion of rib 9 a, closely adjacent to the cylindricalouter lateral wall 25 of axial portion 15 of pin 7.

1) A decelerating device (1) insertable between two members in relativemotion, and comprising a casing (4) defining internally a chamber (5)filled with a viscous fluid (6); and a movable member (7) fitted influidtight manner to the casing, so as to be housed at least partlyinside said chamber and immersed in the viscous fluid; characterized byalso comprising, in combination: partition means (9) for dividing thechamber (5) substantially in fluidtight manner into at least twoadjacent portions (10, 11) varying in volume as a function of theposition of the movable member (7) with respect to the casing (4); andcalibrated constriction means (12; 112; 212) for maintaining permanenthydraulic connection of said at least two adjacent portions (10, 11) ofthe chamber (5), so that said viscous fluid (6) flows, with a given,relatively high resistance, between the chamber portions (10, 11) as aconsequence of the relative motion between the movable member (7) andthe casing (4). 2) A decelerating device as claimed in claim 1,characterized in that said partition means (9) are designed to act assupporting and guide means for said movable member (7) inside saidchamber (5) of the casing. 3) A decelerating device as claimed in claim1, characterized in that said casing (4) is cup-shaped and of elongated,cylindrical axial symmetry like a cigarette; and in that said movablemember is defined by a cylindrical pin (7), which is fitted idly to thecasing, is housed at least partly inside the casing, clicks into anaxially locked position inside the casing, and is inserted through anopen end (14) of the casing; said cylindrical pin comprising an axialportion (15) housed idly in fluidtight manner inside said chamber of thecasing to define a rotor immersed in said viscous fluid filling thechamber; and a head (29) projecting from said open end of the casing. 4)A decelerating device as claimed in claim 3, characterized in that saidhead (29) of the pin and an end (18) of said casing opposite said openend of the casing have angular connecting means (19, 20) for connectionto said members in relative motion, so that said pin (7) and said casing(4) are rotated relatively by said members in relative motion. 5) Adecelerating device as claimed in claim 3, characterized in that saidpartition means (9) comprise: at least one radial rib (9 a) extendingalong the whole length of said axial portion (15) of the pin, and sosized as to cooperate in sliding manner, in use, with a cylindricalinner lateral wall (24) of said chamber of the casing; and asaddle-shaped projection (26) extending along an angular portion ofgiven size of said inner lateral wall of said chamber (5); saidprojection (26) defining a cylindrically symmetrical seat, on which acylindrical outer lateral wall (25) of said axial portion (15) of thepin rests and slides in use; so that said at least one rib (9 a) andsaid projection (26) support and guide said pin inside said chamber. 6)A device as claimed in claim 5, characterized in that said calibratedconstriction means comprise at least one annular groove (12) interruptedby said radial rib (9 a) and formed in said cylindrical outer lateralwall (25) of the axial portion of the pin. 7) A device as claimed inclaim 5, characterized in that said calibrated constriction meanscomprise at least one groove (112) formed, circumferentially withrespect to the axis of symmetry of said pin (7), in a cylindricallysymmetrical surface defining an end edge (113) of said radial rib (9 a)cooperating, in use, with said cylindrical inner lateral wall of thechamber. 8) A device as claimed in claim 5, characterized in that saidcalibrated constriction means comprise at least one hole (212) formed,circumferentially with respect to the axis of symmetry of said pin (7),through a root portion of said radial rib (9 a), closely adjacent tosaid cylindrical outer lateral wall (25) of the axial portion of thepin. 9) A device as claimed in claim 5, characterized in that saidprojection (26) also acts as an angular stop for the rotation of saidpin, by arresting said at least one radial rib (9 a) of the pin onopposite sides. 10) A decelerating device as claimed in claim 5,characterized in that said axial portion (15) and said head (29) of thepin are separated by a cylindrical stop surface (31) larger in diameterthan the axial portion of the pin, and such as to mate idly with saidcylindrical inner lateral wall (24) of said chamber, at said open end ofthe casing; and by a collar (33) which clicks inside a groove formed insaid cylindrical inner lateral wall of the chamber, at said open end ofthe casing; between said cylindrical stop surface and said collar, asealing ring (34) being inserted inside a seat on the pin (7), andcooperating with the cylindrical inner lateral wall of the chamber; andan end of said first axial portion of said pin, opposite said secondaxial portion of the pin, being fitted idly and resting axially inside acylindrical seat (36) defined by a recess formed in said chamber, in anend wall (38) of said casing, and facing said open end of the casing.11) A device as claimed in claim 10, characterized in that, at said endwall end, said casing (4) has an axially projecting pin for receiving,in use, a torsion spring.